A historical perspective on the functional anatomy of reading and writing
Speaker: Professor Cathy Price, Wellcome Trust Centre for Neuroimaging, University College London
23RD APRIL 2013, GORDON MUSEUM OF PATHOLOGY, 6-7.30PM
Over the last 150 years, our understanding of the neural basis of reading and writing has emerged from studies of neurologically impaired patients and functional imaging studies of healthy skilled readers. The first major contribution came from the work of Dejerine (1891,1892) who identified the lesion sites that caused two different types of alexia: Alexia with agraphia described patients who had acquired a deficit in both reading (alexia) and writing (agraphia) and this was associated with damage to the left angular gyrus. The left angular gyrus was therefore linked to memories of visual word forms that are required for both reading and writing. In contrast, alexia without agraphia (which is associated with lesions to the left occipital lobe and the splenium of the corpus callosum) was thought to arise from a disconnection of visual word form processing ( in the left angular gyrus) from visual processing in the occipital cortex. The second major contribution came in the 1970s from reports of alexic patients who had selective difficulty reading either new words (e.g. SHAP) or familiar words whose pronunciation was inconsistent with their spellings (e.g. YACHT). This led to cognitive models of reading that had at least two different reading routes: one that involved word recognition and/or semantics and one that could proceed on sublexical spelling to sound translation. The third major contribution developed in the 1990s with the advent of functional neuroimaging techniques. Early studies aimed to identify the anatomical regions that supported the lexical and sublexical reading pathways that had been predicted by cognitive models of reading. Contrary to expectation, neuroimaging results are not easily reconciled with the current cognitive models but instead show a much more complex reading system that involves multiple brain regions and multiple processing pathways. I will discuss the implication of these anatomical findings for (A) cognitive models of reading and (B) reading ability in patients with neurological damage.
(Taken from UCL website): My research program aims to establish a functional anatomical model of language that predicts how speech and reading are lost and recovered following neurological damage or developmental delay. The hypothesis is that there are multiple ways that the brain can perform each language task (degeneracy). If this is true, then the effect of damage or developmental delay will depend on whether there is a surviving system available to sustain the task.To dissociate the neuronal systems for the same task, we use structural and functional MRI of subjects who vary in their cognitive abilities, demographics and neurological status. This allows us to characterize individual variability in the neuronal networks of neurologically normal populations and to examine how brain damage affects cognitive abilities in patient populations. In particular, we aim to determine how the impact of damage to one system depends on the integrity of another.The language tasks we use are designed to tap various aspects of reading, speech perception, speech production and language control (e.g. in bilinguals). Our studies typically compare the neuronal networks for verbal stimuli to those involved in perceptual, conceptual or motor processing of non-verbal stimuli such as music, environmental sounds, numerals and pictures of objects.